1. Field of the Invention
The invention relates to a method for a multi-function scanner, and more particularly to a method applied to a multi-function scanner capable of scanning a normal document without a laser/anti-counterfeit mark and a special document with the laser/anti-counterfeit mark and capable of effectively removing the laser/and-counterfeit mark from the scanned image.
2. Description of the Related Art
FIG. 1 is a schematic illustration showing a conventional flatbed scanner. As shown in FIG. 1, a scanner 100 is used to scan a to-be-scanned document 200 placed thereon. The scanner 100 includes a guiding rod 120 and a scan module 110 that may be moved along the guiding rod 120. The scan module 110 includes a light source 111, reflecting mirrors 112, a lens module 113, and an image sensor 114.
The light source 111 emits white light rays (visible light rays) to illuminate the document 200, and the light rays are partially reflected to the reflecting mirrors 112, which reflect the light rays to the lens module 113, which focuses the light rays on the image sensor 114. The image sensor 114 converts optical signals into electrical signals, which are processed and then transferred to a computer or other processing devices for further processing. For example, the image signals of the scanned document may be transferred to the computer, which may recognize the image signals into character data.
Since the conventional to-be-scanned documents belong to black/white or color documents, the conventional scanner may scan these documents and obtain good effects. However, laser/anti-counterfeit marks have been added to some important documents, such as ID cards, passports, savings-account books, or other confidential documents in order to prevent the documents from being counterfeited, and the conventional scanner cannot scan these documents with clear effects. This is because the laser/anti-counterfeit marks may shield the information on the documents.
Thus, it is necessary to discriminate if the documents with the laser/anti-counterfeit marks are true or not by the human or machines in the airport, customhouse, or bank, and then to scan the documents with the laser/anti-counterfeit marks using scanners. The scanned image information is then recognized into character information such as numbers and names by processors or computers.
Since the laser/anti-counterfeit marks are typically superimposed on the character information, the scanned image information is typically interfered by the laser/anti-counterfeit marks and becomes blurred when the conventional scanners are used. Therefore, the recognition precision will be influenced and better recognition effects cannot be obtained even if the scan mode is switched to black/white, gray-scale, or color mode.
Thus, it is a great advantage to the user if a scanner can clearly scan a normal document and a special document with a laser/anti-counterfeit mark.
Edgar discloses a method for removing the effect of surface defects from a scan of an image behind a surface using an infrared light source and a visible light source in U.S. Pat. No. 6,075,590. In this disclosure, two scanning processes are performed using the visible light source and the infrared light source to illuminate the document, and the surface defects of the document are removed according to two scanning results. However, no technology with regard to the laser/anti-counterfeit marks has been disclosed.
Taiwan Patent Publication No. 509801 discloses an apparatus for compensating for the optical properties of an object according to light sources with different wavelengths. In this disclosure, the document is scanned twice using a visible light source and an infrared light source to illuminate the document, and then the image are compensated and repaired according to two scanning results. However, no technology with regard to the laser/anti-counterfeit marks has been disclosed.
Thus, it is an important subject of the invention to provide a method applied to a scanner capable of scanning a normal document without a laser/anti-counterfeit mark, and a special document having the laser/anti-counterfeit mark without being influenced by the mark.